Manufacture of abrasive articles



June 1, 1937. E. c. SCHACHT 2,082,182

MANUFACTURE OF ABRASIVE ARTICLES Filed Nov. 20, 1951 amnion Maw PatentedJune 1, 1937 7' UNITED STATES PATENT OFFICE Application November20,1931, Serial No. 576,414

4 Claims.

My invention relates to the manufacture of abrasive articlespand isparticularly concerned with the production of flexible abrasive materialof which one example is sand paper.

5 An object of the invention is to produce a sand paper having a maximumabrading efliciency by means of a process wherein the particles aredispersed to form a uniform coating upon the ad- 1 hesive surface of aweb or carrier.

I have found that if an electrical field be provided between a hopper orother feeding source and the web to be coated, which field will be sosand distribution having the-maximum number of cutting points.

The invention is applicable in'the manufacture of both open coated andclosed coated sand paper and may be used with varying grades and sizesof particles.

In the drawing:

i The figure is a diagrammatic view of the invent on.

Referring to the drawing, the numeral l 0 indicates a hopper in whichare disposed the abrasive particles which, are preferably usuallyemployed in the manufacture of sand paper.

The particle mixture comprises the customary under grade, control grade,and over grade" in which the control grade predominates.

Disposed below the hopper is a suitable gate H which will preferably beadjustable, so as to control the feed of ,the particles from the hopper.The particles are released from the hopper in controlled amounts to aweb II, which is preferably provided with an adhesive surface l3. Theweb may consist of paper, cloth or a laminated material composed ofpaper and cloth, or in fact any usual backing or carrier known in theart is continuously fed in a preferably horizontal direction inaccordance withthe arrow, being supported and carried over suitablerollers ll,-a nd that the lines of force created by the electrical fieldare substantially parallel to the web.

The field is created by reason of the spaced I electrodes I4 and I5, oneof which will be charged and the other grounded. In the presentinstance, I have shown the electrode H as negatively charged and theterminal l5 grounded. Obviously this arrangement can be reversed.

The lines of force of this field, as stated, are parallel to the surfaceof the carrier and are disposed entirely at one side thereof and in thepresent instance above the carrier.

The strength of the field will be varied in accordance with the natureof the particles and the character of the coatingrequired, and can alsobe varied in accordance with the distance of the field from the web. 0

It should be understood also that the feed of 2 the particles may beregulated in accordance with the strength of the electrical field.

Upon reference to the drawing, it will be observed that by reasonof thelines of force set up in the field, the particles become charged andthus mutually repellent, causing them to shower or fan-out.

By reason of this process, I obtain a uniform I dispersement to producea level sand distribution 30 having maximum number of cutting points.

The electrodes 14 and I5 may be agreater or less distance apart,depending upon the article .to be prepared, and the nature of theabrasive particles and, as stated, the strength of the field may bevaried.

By reason of the process, the web having an adhesive surface iscontinuously coated and is only necessary that the feed and the strengthand position of the field be suitably regulated, whence the positions ofthe particles is controlled.

In some cases, I find it desirable to employ a screen or shield Hi toconfine the particles, although this is not essential.

My invention is adapted for the production of either open coated orclosed coated paper and .while I have referred herein to sandspecifically as the abrasive material, it will be understood that otherabrasives of a particle nature are oper-' able with this invention. '5

It will be clear that the gravitational feed of the particles'from thehopper III and feed roller or gate ll, causes them to enter theelectrical field and pass therethrough. Upon becoming charged theparticles are mutually repellent and their direction is changed fromthat due to the gravitational force alone, to a resultant which is thecombined effect of the gravitational force and the respective repellentactions of the particles to each other, plus the action of the lines offorce. In this manner, the dispostion of the particles upon the carrieris controlled to produce the desired eifectsoi' uniform dispersement,resulting in an abrasive surface having the particles permanentlyassociated and possessing a maximum cutting efliciency.

What I claim is:

1. In the art of preparing abrasive articles, wherein abrasive particlesare depositedv upon the adhesive surface of a backing, the steps whichcomprise feeding the particles as individually vseparated bodies to andthrough an electrical field in which the electrodes creating the sameare disposed entirely at one side of the carrier whereby the particlesmust pass through the field in their travel to the carrier, and passingthe particles from the field to adhesive surface of the backing in adirection constituting an alteration of the action of the gravitationalforce due to the mutual repulsiveness' of the particles and to the linesof force created through the field on their way to the carrier,

and passing the particles from the field to the adhesive surface of thebacking in a direction constituting an alteration of the action of thegravitational force due to the mutual repulsiveness of the particles andto the lines of force created by said field whereby the particles areapplied to the adhesively coated backing in dispersed relation.

3. In the art of preparing abrasive articles, wherein abrasive particlesare deposited upon the adhesive surface oi a backing, the steps whichcomprise continuously feeding the particles as individually separatedbodies to and through an electrical field in which the electrodescreating the-same are disposed entirely at one side of the carrierwhereby the particles must pass through the field in theirtravel to thecarrier, and passing the particles from the field to acontinuouslymoving backing having an adhesive surface in adirection constituting analteration of the action of the gravitational force due to the mutualrepulslveness of the particles and to the lines of force created by saidfield whereby the particles are applied to the adhesively coated backingin dispersed relation.

4. In the art 'of preparing abrasive articles, wherein abrasiveparticles are deposited upon the adhesive surface of a backing, thesteps which comprise continuously feeding the particles to and throughan electrical field in which the electrodes creating the same aredisposed entirely at one side of the carrier and having its lines offorce parallel to the surface whereby the particles must pass throughthe field on their way to the carrier, and passing the particles fromthe field to a continuously moving backing having an adhesive surface ina direction constituting an'alteration of the action of thegravitational force due to the mutual repulsiveness of the particles andto the lines of force created by said field whereby the particles areapplied to the adhesively coated backing in dispersed relation.

ELMER C. SCHACHT.

